The objectives of this research are: 1. To define the requirements for and effects of certain metal ions (trace metals), including calcium, manganese, magnesium, iron, copper, cobalt, zinc and tin on growth parameters of the cariogenic organism Streptococcus mutans. These experiments will be conducted in continuous cultures in a chemostat using chemically defined medium (treated to lower trace metal contamination and supplemented with high purity trace metals) under controlled conditions of substrate concentration, trace metal additions, oxygen tension, and pH. 2. To determine the mechanisms of uptake and transport of the above metal ions through kinetic studies for definition of metal ion transport systems and to measure the affinities, specificities, and energy dependence of these systems.